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/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* gimpcoords.c
* Copyright (C) 2002 Simon Budig <simon@gimp.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "core-types.h"
#include "gimpcoords.h"
#define INPUT_RESOLUTION 256
/* amul * a + bmul * b = ret_val */
void
gimp_coords_mix (const gdouble amul,
const GimpCoords *a,
const gdouble bmul,
const GimpCoords *b,
GimpCoords *ret_val)
{
if (b)
{
ret_val->x = amul * a->x + bmul * b->x;
ret_val->y = amul * a->y + bmul * b->y;
ret_val->pressure = amul * a->pressure + bmul * b->pressure;
ret_val->xtilt = amul * a->xtilt + bmul * b->xtilt;
ret_val->ytilt = amul * a->ytilt + bmul * b->ytilt;
ret_val->wheel = amul * a->wheel + bmul * b->wheel;
ret_val->velocity = amul * a->velocity + bmul * b->velocity;
ret_val->direction = amul * a->direction + bmul * b->direction;
ret_val->extended = b->extended || a->extended;
}
else
{
ret_val->x = amul * a->x;
ret_val->y = amul * a->y;
ret_val->pressure = amul * a->pressure;
ret_val->xtilt = amul * a->xtilt;
ret_val->ytilt = amul * a->ytilt;
ret_val->wheel = amul * a->wheel;
ret_val->velocity = amul * a->velocity;
ret_val->direction = amul * a->direction;
ret_val->extended = a->extended;
}
}
/* (a+b)/2 = ret_average */
void
gimp_coords_average (const GimpCoords *a,
const GimpCoords *b,
GimpCoords *ret_average)
{
gimp_coords_mix (0.5, a, 0.5, b, ret_average);
}
/* a + b = ret_add */
void
gimp_coords_add (const GimpCoords *a,
const GimpCoords *b,
GimpCoords *ret_add)
{
gimp_coords_mix (1.0, a, 1.0, b, ret_add);
}
/* a - b = ret_difference */
void
gimp_coords_difference (const GimpCoords *a,
const GimpCoords *b,
GimpCoords *ret_difference)
{
gimp_coords_mix (1.0, a, -1.0, b, ret_difference);
}
/* a * f = ret_product */
void
gimp_coords_scale (const gdouble f,
const GimpCoords *a,
GimpCoords *ret_product)
{
gimp_coords_mix (f, a, 0.0, NULL, ret_product);
}
/* local helper for measuring the scalarproduct of two gimpcoords. */
gdouble
gimp_coords_scalarprod (const GimpCoords *a,
const GimpCoords *b)
{
return (a->x * b->x +
a->y * b->y +
a->pressure * b->pressure +
a->xtilt * b->xtilt +
a->ytilt * b->ytilt +
a->wheel * b->wheel +
a->velocity * b->velocity +
a->direction * b->direction);
}
/*
* The "length" of the gimpcoord.
* Applies a metric that increases the weight on the
* pressure/xtilt/ytilt/wheel to ensure proper interpolation
*/
gdouble
gimp_coords_length_squared (const GimpCoords *a)
{
GimpCoords upscaled_a;
upscaled_a.x = a->x;
upscaled_a.y = a->y;
upscaled_a.pressure = a->pressure * INPUT_RESOLUTION;
upscaled_a.xtilt = a->xtilt * INPUT_RESOLUTION;
upscaled_a.ytilt = a->ytilt * INPUT_RESOLUTION;
upscaled_a.wheel = a->wheel * INPUT_RESOLUTION;
upscaled_a.velocity = a->velocity * INPUT_RESOLUTION;
upscaled_a.direction = a->direction * INPUT_RESOLUTION;
return gimp_coords_scalarprod (&upscaled_a, &upscaled_a);
}
gdouble
gimp_coords_length (const GimpCoords *a)
{
return sqrt (gimp_coords_length_squared (a));
}
/*
* Distance via manhattan metric, an upper bound for the eucledian metric.
* used for e.g. bezier approximation
*/
gdouble
gimp_coords_manhattan_dist (const GimpCoords *a,
const GimpCoords *b)
{
gdouble dist = 0;
dist += ABS (a->pressure - b->pressure);
dist += ABS (a->xtilt - b->xtilt);
dist += ABS (a->ytilt - b->ytilt);
dist += ABS (a->wheel - b->wheel);
dist += ABS (a->velocity - b->velocity);
dist += ABS (a->direction - b->direction);
dist *= INPUT_RESOLUTION;
dist += ABS (a->x - b->x);
dist += ABS (a->y - b->y);
return dist;
}
gboolean
gimp_coords_equal (const GimpCoords *a,
const GimpCoords *b)
{
return (a->x == b->x &&
a->y == b->y &&
a->pressure == b->pressure &&
a->xtilt == b->xtilt &&
a->ytilt == b->ytilt &&
a->wheel == b->wheel &&
a->velocity == b->velocity &&
a->direction == b->direction);
/* Extended attribute was omitted from this comparison deliberately,
* it describes the events origin, not its value
*/
}
/* helper for calculating direction of two gimpcoords. */
gdouble
gimp_coords_direction (const GimpCoords *a,
const GimpCoords *b)
{
gdouble direction;
gdouble delta_x, delta_y;
delta_x = a->x - b->x;
delta_y = a->y - b->y;
if ((delta_x == 0) && (delta_y == 0))
{
direction = a->direction;
}
else if (delta_x == 0)
{
if (delta_y > 0)
direction = 0.25;
else
direction = 0.75;
}
else if (delta_y == 0)
{
if (delta_x < 0)
direction = 0.0;
else
direction = 0.5;
}
else
{
direction = atan ((- 1.0 * delta_y) / delta_x) / (2 * G_PI);
if (delta_x > 0.0)
direction = direction + 0.5;
if (direction < 0.0)
direction = direction + 1.0;
}
return direction;
}
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